U.S. patent number 5,595,413 [Application Number 08/355,085] was granted by the patent office on 1997-01-21 for fluid actuated gripper.
This patent grant is currently assigned to Numation, Inc.. Invention is credited to Donald E. McGeachy, Jeffrey R. Schneid.
United States Patent |
5,595,413 |
McGeachy , et al. |
January 21, 1997 |
Fluid actuated gripper
Abstract
A fluid actuated gripper mechanism with opposed gripper slides
received on ways of a housing and actuated by opposed pistons
received in a common bore. Each piston is transfixed by a coupling
pin secured to one slide. Movement of the pistons and slides is
synchronized by a lever pivotally mounted in the housing and having
equally radially spaced apart and parallel elongate cam slots in
which the coupling pins are received.
Inventors: |
McGeachy; Donald E. (Commerce
Township, MI), Schneid; Jeffrey R. (North Olmstead, OH) |
Assignee: |
Numation, Inc. (Westlake,
OH)
|
Family
ID: |
23396176 |
Appl.
No.: |
08/355,085 |
Filed: |
December 12, 1994 |
Current U.S.
Class: |
294/207;
294/119.1; 901/37 |
Current CPC
Class: |
B25J
15/0253 (20130101) |
Current International
Class: |
B25J
15/02 (20060101); B25J 015/08 () |
Field of
Search: |
;294/88,93,119.1
;269/25,27,32,34 ;901/36,37,39 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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22331 |
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Jan 1981 |
|
EP |
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0208863 |
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Jan 1987 |
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EP |
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0344954 |
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Dec 1989 |
|
EP |
|
3806148 |
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Sep 1988 |
|
DE |
|
19513739 |
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Oct 1995 |
|
DE |
|
812569 |
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Mar 1981 |
|
SU |
|
2041262 |
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Sep 1980 |
|
GB |
|
Primary Examiner: Cherry; Johnny D.
Attorney, Agent or Firm: Barnes, Kisselle, Raisch, Choate,
Whittemore & Hulbert
Claims
What is claimed is:
1. A fluid actuated gripper mechanism of the type having opposed
gripper devices mounted for sliding relation to and from a gripping
position which comprises:
(a) a housing,
(b) opposed gripper slides mounted on said housing for lineal
reciprocation,
(c) a piston bore extending axially of said housing adjacent said
slides,
(d) opposed pistons in said bore,
(e) coupling pins coupling said pistons to said slides, each said
coupling pin transfixed one piston and has a first end extending
into a gripper slide to cause simultaneous motion of said one
piston and slide, and
(f) a synchronizing lever located in said body, centrally mounted
to pivot on an axis perpendicular to the axis of said piston bore,
said lever having parallel cam slots, one at each end, angled to
the path of lineal reciprocation of said slides, and a second end
of each said transfer pin is located in a respective cam slot to
provide simultaneous synchronous motion of said pistons and slides
when actuated, wherein fluid directed to said pistons actuates said
slides simultaneously.
2. A fluid actuated gripper mechanism as defined in claim 1 in
which an elongate recess is formed in said housing adjacent said
piston bore, a central pivot in said recess mounting said lever in
said recess and a closure plate closing said recess to avoid
contamination of said lever and pins.
3. A fluid actuated gripper mechanism as defined in claim 1 which
also comprises end plates on said housing to close said piston
bore, and passages in at least one of said end plates and said
housing to direct operating fluid to the outer ends of said pistons
to produce a gripping motion and to the inner ends to produce a
release motion.
4. A fluid actuated gripper mechanism as defined in claim 1 which
also comprises a clearance slot associated with each coupling pin
through which it extends adjacent its associated slide, each said
clearance slot underlying and being closed by its associated slide
regardless of the position of its associated piston to prevent
contaminants from entering the piston bore through said clearance
slot.
5. A fluid actuated gripper mechanism comprising: a housing having
sides and a pair of opposed ends, a slot in said housing opening
through a side and extending longitudinally through the housing and
opening into its opposed ends to provide ways for slides, a pair of
generally opposed gripper slides received in said slot for linear
reciprocal movement, a bore extending axially through the housing
and opening into the opposed ends of the housing, a pair of opposed
pistons received in said bore, a synchronizing lever carried by the
housing and centrally mounted to pivot on an axis perpendicular to
the axis of the bore, said lever having a pair of parallel cams one
adjacent each end of the lever, said cams being inclined to the
path of reciprocal motion of the slides, and a separate pin
extending transversely through each piston and having a first end
coupled with an associated gripper slide to cause simultaneous
motion of the one piston and associated gripper slide, and a second
end engaging with an associated one of the cams of the lever to
provide simultaneous synchronous motion of the pistons and slides
when actuated, whereby fluid directed to the pistons synchronously
moves the slides simultaneously.
6. A fluid actuated gripper mechanism as defined in claim 5 in
which a recess is formed in said housing adjacent said bore, a
central pivot in said recess mounts said lever in said recess and a
closure plate closes said recess to avoid contamination of said
lever and pins.
7. A fluid actuated gripper mechanism as defined in claim 5 which
also comprises end plates on said housing to close said bore, and
passages in at least one of said end plates and said housing to
direct operating fluid to the outer ends of said pistons to produce
a gripping motion and to the inner ends to produce a release
motion.
8. A fluid actuated gripper mechanism as defined in claim 5 which
also comprises a clearance slot in said housing and associated with
each coupling pin through which it extends adjacent its associated
slide, each said clearance slot underlying and being closed by its
associated slide regardless of the position of its associated
piston to prevent contaminants from entering the piston bore
through said clearance slot.
Description
FIELD OF INVENTION
This invention relates to a fluid actuated gripper mechanism for
engaging, handling and releasing work parts by a pair of opposed
movable jaws.
BACKGROUND OF THE INVENTION
Work gripping mechanisms for handling work parts are especially
useful in automated equipment, such as at the end of robotic arms
which move parts as desired in a production process. Fluid
actuation is desirable since it allows operation remote from the
source of fluid pressure and control valves.
One example of a gripper assembly is found in U.S. Patent to Borcea
at al, U.S. Pat. No. 5,163,729, issued Nov. 17, 1992, which
discloses a mechanism using opposed fluid actuated jaws with a rack
and pinion arrangement synchronizing movement of the jaws.
SUMMARY OF THE INVENTION
A gripper with a pair of opposed slides is received in a common way
of a housing and actuated by a pair of opposed pistons received in
a common cylinder bore in the housing. Movement of the pistons and
slides is synchronized by a synchronizing lever centrally pivotally
mounted and enclosed within the housing and having equally radially
spaced apart cams preferably in the form of elongate and parallel
slots adjacent opposed ends of the lever. Preferably, each slide,
piston and one cam are operably connected by a pin slidably
received in the cam slot, extending transversely through the piston
and secured to the slide. Preferably, the pistons are received
between the slides and the synchronizing lever and the pistons,
pins and lever are completely enclosed in the housing to prevent
contamination of the mechanism. If desired, the piston can be
spring biased and fluid actuated in one or both directions. For
applications where the pistons and slides need not be synchronized,
the lever and cams can be omitted. The pistons will also stabilize
and provide a guide for reciprocable movement of the pins.
Preferably, the opposed ends of the cylinder bore are closed by
cover plates releasably secured to the housing and preferably
contain ports for directing fluid to actuate the pistons.
Objects, features and advantages of this invention are to provide a
gripper in which movement of the slides and pistons is easily and
accurately synchronized, the operating mechanism is enclosed to
prevent exposure, contamination and damage, the slides, pistons and
sychronizers are simply and easily operably coupled together, and
the gripper can be produced in a wide range of sizes and is
extremely compact, lightweight, simple, rugged, durable, reliable,
quick and easy to use, of relatively simple and economical design,
manufacture and assembly and in service has a long useful life and
requires little maintenance.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects, features and advantages of the invention
will be apparent from the following detailed description of the
preferred embodiment and best mode, appended claims and
accompanying drawings in which:
FIG. 1 is a longitudinal sectional assembly view of a gripper
mechanism embodying the invention;
FIGS, 2, 3 and 4 are views taken respectively at lines 2--2, 3--3
and 4--4 of FIG. 1;
FIG. 5 is a bottom view of a synchronizer lever, taken on FIG. 1
with the bottom plate removed; and
FIG. 6 is a longitudinal sectional view taken on line 6--6 of FIG.
2.
DETAILED DESCRIPTION
Referring in more detail to the drawings, FIG. 1 illustrates a
gripper 10 embodying this invention with a pair of opposed slides
12 & 14 carried by a housing 16 and actuated by a pair of
opposed pistons 18 & 20. Reciprocable movement of the slides
and pistons is synchronized by a synchronizer mechanism 22. Ways
and guides for reciprocation of the slides are provided by a slot
24 with a T-shape cross section which opens through the top of the
housing and extends longitudinally completely through the housing
and opens into its opposed ends 26 & 28. Preferably, for
mounting the gripper, a dovetail 30 extends longitudinally across a
side of the housing for complementary engagement with a mounting
block 32 which may be secured to the end of a robot, on a transfer
device, a machine tool, or the like.
Preferably, the pistons 18 & 20 are slidably received in a
common bore 42 through the housing. Preferably, to decrease the
weight of the pistons, they have blind bores 46 & 48 in their
opposed ends. The ends of the bore 42 are closed by end plates 52
and 54 secured to the housing by cap screws 56. Suitable seals 58,
such as O-rings, are disposed between them. If it is desired to
yieldably bias the slides and pistons away from each other, a
suitable compression spring 60 is disposed in the opposed blind
bores 46 of the pistons. If it is desired to yieldably bias the
slides and pistons toward each other, the spring 60 is omitted and
a pair of suitable compression springs are disposed in the blind
bores 48 of the pistons with one spring end bearing on the adjacent
end plate 52 or 54.
Workpiece gripper blocks or fingers 72 & 74 are mounted on and
secured to the slides 12 and 14. Each slide has a pair of
longitudinally extending slots 76 providing a complementary
generally H-shaped cross section with complementary interfitting
surfaces engaging the ways of the housing formed by the T-shaped
slot 24. The slides are retained on the ways of the housing and
operably connected with the pistons by coupling pins 82 and 84
transfixed or slidably received in bores through the pistons and
with the upper end of each pin threaded into a blind bore in the
slide.
Adjacent both ends, each piston is provided with a fluid tight seal
between the piston and bore 42 by annular seals 86 & 88. To
provide clearance for movement of the coupling pins 82 & 84
with the pistons, elongate slots 90 and 92 are provided in the bore
42 and housing 16 through which the pins pass. To prevent escape
through the slots of fluid pressure acting on the pistons, the
slots 90 and 92 adjacent each piston lie longitudinally between the
seals 86 and 88 of the piston regardless of whether the piston is
fully retracted (as shown in FIG. 1), or fully extended. To prevent
contaminants from entering the sleeve through the upper slots 92,
they are always covered by their associated slide 12 or 14
regardless of the extended or retracted position of the slide and
preferably, to provide a seal, the lower face of each slide bears
on the underlying face of the T-shape slot 24 in the housing.
The synchronizing mechanism 22 is received in a cavity 100 in the
bottom of the housing which is closed and sealed by a cover plate
102 releasably secured in a recess in the housing by cap screws
103. The synchronizer has a lever 120 pivoted on a centrally
located pin 108 journalled for rotation by a pair of opposed
bearings 104 & 106 (FIGS. 1 and 4) received in opposed circular
recesses in the housing 16 and the cover plate 102. The lever 120
has adjacent its end two cam slots 122 & 124 through which the
lower ends of the coupling pins 82 & 84 extend and engage the
side walls of the slots. The elongate cam slots are parallel to
each other, diametrically opposed and equally radially spaced from
the axis of pin 108 on which they pivot. Preferably, the pins have
a "close fit" sliding engagement with the cam slots.
As shown in FIG. 5, movement of the piston 18 and its coupling pin
82 from its solid line position to its phantom broken line position
through the axial or longitudinal distance designated at A will in
cooperation with the cam slot 122, rotate the lever
counterclockwise and through the cooperation of cam slot 124 with
the coupling pin 84 will move the pin 84 and its associated piston
20 through an equal longitudinal or axial distance B from the solid
line to the phantom line position of the pin 84. This movement of
either piston in either axial direction will cause through the
cooperation of the coupling pins, cam slots and lever, movement of
the other piston an equal distance. Thus, the sychronizing
mechanism 22 will insure that the pistons and their associated
slides will always move in precise and accurate synchronism at all
times.
The pistons also serve as guides which stablize and prevent the
pins from tilting or cocking relative to the longitudinal axis of
the bore 42 thereby insuring smooth and accurate movement without
binding of the synchronizing mechanism and the slides. Disposing
the slides and the synchronizing lever and cams on opposite sides
of the pistons also tends to better balance the forces acting and
reacting on the slides and synchronizing mechanism when the
gripping blocks and fingers on the slides are forced into and
maintained in engagement with a workpiece by pressurized fluid
acting on the pistons.
The pistons are actuated by a hydraulic or pneumatic fluid under
pressure. The pistons are moved inwardly by fluid under pressure
acting on their outer ends 134 and 138 which is admitted through
the port 130 in end plate 52 (FIGS. 1 and 2). Fluid from port 130
is admitted to the outer face 134 of piston 18 through connecting
passages 132 and 133. Simultaneously, fluid under pressure is
admitted to the outer face 138 of piston 20 through a passage 136
extending longitudinally through the housing 16 and an
interconnecting transverse passage 137 in end plate 54. If desired,
when the fluid pressure is relieved through port 130, the pistons
and slides can be retracted or moved outwardly by the bias of the
compression spring 60. However, in many applications, it is
preferable to positively return and retract the pistons and hence
the slides by both relieving the fluid pressure at port 130 and
simultaneously applying fluid pressure to the inner ends of the
pistons to force them outwardly.
Fluid is supplied to the inner ends of the pistons through the port
142 in end plate 52 which communicates with the chamber 143 between
the inner ends of the pistons through an interconnecting passage
144 extending longitudinally into the housing from its end 26 and a
transverse passage 146 which opens into the chamber 143 between the
pistons.
In use, the gripper 10 is typically mounted on a workpiece transfer
device, such as the end of the arm of a robot. The ports 130 and
142 are connected to a source of fluid pressure such as compressed
air through a suitable control valve, such as a solenoid actuated
four way control valve. Typically, the grippers 72 and 74 are
arranged on the slides so they will be disengaged from the
workpiece when the slides and pistons are in the retracted position
as shown in FIG. 1. To engage a workpiece, the gripper is properly
positioned by the robot and the solenoid valve is energized to
supply compressed air through the port 130 to act on the outer
faces 134 & 138 of the pistons to move them and the slides
inward into firm engagement with the workpiece which is then
transferred by the robot while held by the grippers.
After the desired operation or operations are performed, the
workpiece is transferred by the robot, then released by the gripper
10. The workpiece is released by actuating the solenoid valve to
relieve the compressed air through port 130 and to supply
compressed air through the port 142 to act on the inner ends of the
pistons to move them outwardly to their retracted positions along
with the slides so that the grippers disengage and release the
workpiece. The movement of the pistons and the slides is
synchronized by the cooperation of the coupling pins 82 and 84 with
the cam slots 122 and 124 and the lever 120.
It will be appreciated that some types of workpieces will be
engaged by moving the slides outward and disengaged and released by
moving the slides inward. This can be accomplished by reversing the
application and relief of fluid pressure to the ports 130 and 142
from the sequence just discussed and hence will not be stated in
further detail since it will be apparent to skilled persons.
* * * * *